To meet the demand for wireless data traffic having increased since deployment of 4th generation (4G) communication systems, efforts have been made to develop an improved 5th generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (COMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
The concept of addition of a plurality of transmission antennas, which is frequently called a huge or large scale MIMO system, has drawn attention from the industrial world and the academic world over the years. To easily obtain a beamforming gain and/or a spatial multiplexing gain in the large scale MIMO system, channel state information (CSI) between a transmitter and a receiver is essential for the transmitter. Time division duplexing (TDD) assumes that the transmitter in the large scale MIMO system depends on the channel reciprocity to have CSI without transmitting a pilot and estimating/feeding back a channel. However, an effective approach method for acquiring CSI in the large scale MIMO system has been discussed since most of the cellular systems adopted frequency division duplexing (FDD).